A study of thousands of dentists found that the absorption of mercury is associated with an increased risk of tremors. Published in the Journal of the American Dental Association, the study followed 13,906 dentists for a 24-year period.

The research tested the dentists’ urinary mercury levels to estimate their individual exposure. The incidence of tremors—the involuntary shaking of hands, arms and other parts of the body—among the dentists was then compared with their exposure to mercury.

Higher exposures to mercury increased the risk of tremors among the entire population of dentists studied by 10 percent; the increased risk among the young dentists was 13 percent.